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Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit
Electromagnetic absorbers based on ultra-thin metallic film are desirable for many applications such as plasmonics, metamaterials, and long-wavelength detectors. A metallic film will achieve a maximum 50% of electromagnetic wave absorption, frequency independent, at a thickness defined by its conduc...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group UK
2022
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9626603/ https://www.ncbi.nlm.nih.gov/pubmed/36319666 http://dx.doi.org/10.1038/s41598-022-23119-7 |
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author | Haddadi. M, Mahsa Das, Bamadev Jeong, Jeeyoon Kim, Sunghwan Kim, Dai-Sik |
author_facet | Haddadi. M, Mahsa Das, Bamadev Jeong, Jeeyoon Kim, Sunghwan Kim, Dai-Sik |
author_sort | Haddadi. M, Mahsa |
collection | PubMed |
description | Electromagnetic absorbers based on ultra-thin metallic film are desirable for many applications such as plasmonics, metamaterials, and long-wavelength detectors. A metallic film will achieve a maximum 50% of electromagnetic wave absorption, frequency independent, at a thickness defined by its conductivity, typically in the sub-Angstrom range for good metals if bulk conductivity is maintained throughout. This makes it extremely difficult to obtain substantial absorption from thin metal films, in contrast to 2D materials such as graphene. Luckily, however, from a practical point of view, metal conductivity is drastically reduced as the film becomes sub-100 nm, to make it a race between the thinnest possible metal thickness experimentally achievable vs the conductivity reduction. Here, we demonstrate a near-50% absorption at a gold film thickness of 6.5 nm, with conductivity much reduced from the bulk value, down to the range of 10(6) Siemens per meter. Studying the effect of the substrate thickness, we found that the common cover glass, with its thickness much smaller than the wavelength, achieves symmetric absorption of 44%, implying that a pseudo-free-standing limit is achieved. Our work may find applications in infrared sensing as in bolometers and biomedical sensing using microwaves. |
format | Online Article Text |
id | pubmed-9626603 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | Nature Publishing Group UK |
record_format | MEDLINE/PubMed |
spelling | pubmed-96266032022-11-03 Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit Haddadi. M, Mahsa Das, Bamadev Jeong, Jeeyoon Kim, Sunghwan Kim, Dai-Sik Sci Rep Article Electromagnetic absorbers based on ultra-thin metallic film are desirable for many applications such as plasmonics, metamaterials, and long-wavelength detectors. A metallic film will achieve a maximum 50% of electromagnetic wave absorption, frequency independent, at a thickness defined by its conductivity, typically in the sub-Angstrom range for good metals if bulk conductivity is maintained throughout. This makes it extremely difficult to obtain substantial absorption from thin metal films, in contrast to 2D materials such as graphene. Luckily, however, from a practical point of view, metal conductivity is drastically reduced as the film becomes sub-100 nm, to make it a race between the thinnest possible metal thickness experimentally achievable vs the conductivity reduction. Here, we demonstrate a near-50% absorption at a gold film thickness of 6.5 nm, with conductivity much reduced from the bulk value, down to the range of 10(6) Siemens per meter. Studying the effect of the substrate thickness, we found that the common cover glass, with its thickness much smaller than the wavelength, achieves symmetric absorption of 44%, implying that a pseudo-free-standing limit is achieved. Our work may find applications in infrared sensing as in bolometers and biomedical sensing using microwaves. Nature Publishing Group UK 2022-11-01 /pmc/articles/PMC9626603/ /pubmed/36319666 http://dx.doi.org/10.1038/s41598-022-23119-7 Text en © The Author(s) 2022 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . |
spellingShingle | Article Haddadi. M, Mahsa Das, Bamadev Jeong, Jeeyoon Kim, Sunghwan Kim, Dai-Sik Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit |
title | Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit |
title_full | Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit |
title_fullStr | Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit |
title_full_unstemmed | Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit |
title_short | Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit |
title_sort | near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9626603/ https://www.ncbi.nlm.nih.gov/pubmed/36319666 http://dx.doi.org/10.1038/s41598-022-23119-7 |
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